Methods for the purification of African swine fever virus (ASFV) and its dissection into two fractions are described. The difficulties which have been encountered previously in attempts to purify the virus, namely contamination with large amounts of cellular constituents and aggregation of the virus particles, have been overcome by treatment with Tween 80 and by the use of 1 M-NaCl in the sucrose gradients. Five major polypeptides, mol. wt. 10(3) X 125 (VP1), 76 (VP2), 50 (VP3), 44 (VP4) and 39 (VP5) were found in the purified particles. The virus was dissected by treatment with Nonidet NP 40 into (a) a fraction which had the appearance of an empty capsid shell and capsid shell and contained the polypeptides VP2 and VP3 and (b) a structure containing VP1 and VP4. The location of VP5 was not ascertained.